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Sweet sensation

By Piers Wehner

The gene behind the most seductive of taste sensations – sweetness – has been at last identified.

Receptors for the four others, bitter, sour, salty and umami, had already been tracked down. Now researchers at the Mount Sinai School of Medicine in New York believe they have found the fifth, tucked away on the end of chromosome 4.

Robert Margolskee, who led the team, believes that the research could lead to the development of designer sweeteners. “Drinks manufacturers are always complaining that their sugar substitutes don’t taste right – that they don’t have that durability or roundness of flavour,” he said.

“But if this gene encodes a receptor protein then one should be able to use this as a target to design a stronger substitute,” Margolskee concluded.

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Margolskee’s team has located the gene on the human genome, but he says many more tests will be needed before they can say for certain whether it is responsible for an individual’s weakness for sweetness.

The Mount Sinai team identified mice proteins similar to the receptors for bitterness and umami. They then examined mouse strains which were unable to taste sugars or sweeteners and found that they all had mutations in a gene called T1R3, strongly suggesting that this is the blueprint for the receptor for sweetness

Testing the sensitivity of the mice to sugar had its own challenges, according to Margolskee&colon; “If you want to know if a human likes sugar, you just ask them. Its a bit hard to ask a mouse if they want one lump or two. So we used a two-bottle taste test – one bottle with normal water, and one that has a sugar solution.”

Similar results have been published by a team from Harvard Medical School in Nature Neuroscience.